NEC and NTT completed a transoceanic-class 7,280km transmission experiment using a coupled 12-core multicore fiber, which consists of 12 optical signal transmission paths in a standard outer diameter optical fiber (0.125 mm).
MIMO technology, which is crucial for separating interfering radio signals, has been limited in optical communications to handling just two-polarization multiplexed signals due to the complexity of signal processing. This limitation is even more pronounced in multicore fiber optics, where signals are multiplexed across several cores, requiring advanced signal processing to manage issues like crosstalk during long-distance transmission. NEC has developed an algorithm that tackles these challenges, enabling the efficient separation and demodulation of signals in a 24 x 24 MIMO system (12 cores x 2 polarizations) for long-distance optical communications.
Meanwhile, NTT has focused on overcoming the difficulties in long-haul optical communications caused by non-uniform delays and losses among multiplexed signals in multicore fiber. By developing coupled multicore fiber and optical devices that minimize the effects of these non-uniformities, NTT aims to facilitate MIMO signal processing and extend the feasible transmission distance.
